We started up a mold that runs with PVC. We are surface drying the PVC at 165. When we introduce the PVC into the barrel, we can run a couple of shots, then the pvc quits feeding into the barrel. After a while it finally charges all of the way, then it wont feed again the next cycle. Then I put some purging compound into the hopper and it purges just fine.

We noticed that when we take the magnets out from the hopper, that they are oily. I drained the hopper and the pvc that came out was oily. So I drew the PVC straight from the gaylord and bypassed the dryer and everything worked fine.

Why would the PVC become oily in the dryer and why would that keep it from feeding into the barrel.